<div class="panel panel-default">
  <div class="panel-heading">站内搜索</div>
  <div class="panel-body">

    <form action="{% url 'search' %}" method="get">
{#        输入框组合#}
        <div class="input-group">
            <input type="text" name="key" class="form-control" value="{{ key }}">
{#            输入框组合的按钮#}
            <span class="input-group-btn">
                <button class="btn btn-default" type="submit">
                    <span class="glyphicon glyphicon-search"></span>
                </button>
            </span>
        </div>
    </form>

  </div>

</div>